Formic acid.



UNITED STATES PATENT OFFICE.

m NEUMANN, or wmsaanrnv, enn ma'nx, assrenon ro GENERAL CHEMICAL comrm, on ,NEW xonx, N. x., a CORPORATION on NEW YORK.

- roux- ACID.

$75,151, Specification of Letters Patent. Patented NOV, 8, 191 lemming. Application filed June a, 1910. Serial No. 566,017.

i To all whom it may concern:

invention is based upon the discovthis temperature diminishes,-

- dred and .Be it known that I, Max NEUMANN, a subject of .the Em ror of Germany, and resident of Wiesba' en, German, have invented certain new and usefu Improvements in the Production of Formic Acid, of which the following is. a specification.

' This invention relates to'the production of formic acid by the decomposition of a formate by means of phosphoric acid. Strong anhydrous formic acid may be obtained by this process as well as weaker or dilute qualities thereof.

ery made by me that, contrary to recorded experience .(see, foncxample, U. S. Patent 857,0;6 to Francke, p. 1, lines 15 to 19) phosphoric acid can be used for the liberation of formic acid from formate without any substantial loss of formicacid due to, decomposition thereof by any of the phosphoric acid used. I 'i' In the following I give an example of car.- rying out this, my invention, and in so do wish to be understoodias not limiting myself to the exact details therein given since these may bevaried without departing from this, my invention. The parts are by weight. Example; 375), parts of dried and very finely edpowered sodium formate and one hundr sixty-four (164) parts of-phosphoric acid containing eighty-seven (87) per cent. of absolute phosphoric acid (H30 during the production of this mixture the tempera: ture of the mass rises 'and may reach fifty (50) orsixty degrees centigrade; when raise it to, a

oint between seventy (70) and one hundred (100) degrees centigrade by means of an oil bath and maintain it there fora period of from fifteen .(15) to thirty (30) minutes; then raise the temperature ,to a oint where distillation begins .and gradu y increase it until distillation ceases, but do not raise the temperature of the .inassabove one'hunforty-five (14:5) degrees centiade. The stronger acid. comes off first; as the distillation approaches its end, the disthat is to say when they are at work room or normal temperature, so that the Intimately seventy-five and solute phosphoric acid (H P sixty-four (164) parts 0 eighty-seven (87) (99) parts of a p I ninety-four 294) per cent.

higher 13b8 the'degree above indicated. However, the desired result may be obtained even though the ingredients are slightly heated, provided that the mixture does not jointly possess a 'temperaturehigher than will, together with the temperature created .by the reaction, reach a point at which the formic acid 1s 'decoin ed. Therefore, when .I speak in the claims of mixing the ingredients without the addition of heat I temperature during reaction does not rise desire it to be considered as equivalent thereto if I mix them at any degree-of temperature which will enable the rocess-to take place w thoutthe addition 0 a diluent and without the decomposition of formic acid. It will probably be found thatv the temperature of the mixture should not atany time during the reaction be hi herthan 100 C. under normal conditions i theobjec ofmy invention is to be attained. Byapplying a partial vacuum to the distilling apparatus, a lower temperature may be used and the time required for carrying out the operation is reduced. This use 0 a partial vacuuml has the further advantage that the residue in the distilling vessel may be obtained as a porous mass and conveniently removed from the distillin vessel-by treatment with hot water. In t is way-I have been able to obtain 95.5% of the formic acid contained in the sodium formate used in the distillate and having an aver e strength of 63.1% of formic acid (H 0 H). stronger phosphoric acid, for containing ninety-four (94) By the use of example, such- I have been able to obtain 99 per cent. of the formic acid contained in the sodium formats used in the distillate and having an average-strengthof 7 0.6% also 'found acid employed ma so that instead 0 be reduced considerably usin phosphoric acid of per cent. (strength ,of the above exam le') I can use as little -as one hundred and eight (108) or even ninety-nine hosphoricacid containingof absolute p'hosphoric acid, 11,1 0 butin these casesthe relative amount of orinic acid obtained'in the-distillate is-smaller. I

It is notne'cessary to usepure phosphoric -a cid to obtain results above g1ven; crude one hundred and Sil or cent. of ab of formic acid (HCo H). .1 have that. the amount of phosphoric interactin that drie phosphoric acid contaminated with. i1'

alumlna and like things canbe em 105 0 3 without materially affectingv the us ity or quantit'yof the formic acid produce ,particularly not if care be exercised in producing and maintaining an intimate mixture of the materials. I have also found phoslphate or a mixture containing it can be emp oyed in placeof phosphoric acid, suitable amounts of said monosodium phosphate being used. In-place of sodium formats I may use other for-mates, such as potassium formate and ammonium formate.

I claim:

1. The process of making fortnic acid which consists in causing a formats and hosphoric acid to interact at a temperature below that 'at which the formic acid is decomposed,substantially pose described.

.2." In the processof making formic. acid I -the step which consists in mixing 9. formats and phosphoric acid and allowinp'the same to interact ,without'the addition 0 heat, substant'ially as and for the purpose described.

3. In the process of-inaking formic acid the step which consists in mixing a formate and phosphoric acid and allowing the same tointeract at-a tex'nperaturebe'low that at which. the formic acid is decomposed sub- I 5. The process of making formicacid vscri and finely ground monosodium' 'dition of heat until-there isno 1011 rise in tem as and for the purthen isolating theformic acid so produced {my hand inthe witnesses.

which in causing a. fol-"mate and 1 phosphoric acid'to interact without the adition of blast until there is. no longer any rise in tempcratui edue tolthe reaction, and

substantially as bold.

6. which hi and for thelpurpose deeo'ns'is'ts in causing a 'formate and phosphoric acid to interact without the addition of heat until-there is no longer any rise in temperature "due to the reaction and to need thenisolating the, formic acid so by distillation, substantially as an for the purpose described.-

The process which consists -in, causing' a formats and of making formic acid:

thenv isolatingthe iormic acidso produced, v

' process of making formic acid phosphoric acidf'to' interact without the ader any erature due to-th'e reaction and by distillation under diminished pressure,

substantially as and for the, purpose do scribed.

- 8. The was at jmalringfanhydrous formic aci I which consists in causing sodium formats to purpose described v *Intestimony whereof I have'lin'unto set j N m-m;

v H RMAN PLIBCH L."

react with phosphoric acid, of a 'strengthbetween 92% and 95% of absolutephosphoric acid, H BO witli-outthe addi tion; of heat substantially as and for the presence of two subscribing 

